Preparation, properties and metabolism of 5,6-monoepoxy-3-dehydroretinal.
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ABSTRACT:
SUBMITTER: Mallia AK
PROVIDER: S-EPMC1187489 | biostudies-other | 1969 Jan
REPOSITORIES: biostudies-other
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Project description:1. Methyl retinoate has been converted into methyl 5,6-monoepoxyretinoate by reaction with monoperphthalic acid. The epoxy acid ester on alkaline hydrolysis gave 5,6-monoepoxyretinoic acid. 2. Treatment of the 5,6-monoepoxy compounds with ethanolic hydrochloric acid gave the corresponding 5,8-epoxy (furanoid) compounds. 3. With lithium aluminium hydride, the acid and the ester groups were selectively reduced to primary alcohols. 4. Administration of methyl 5,6-monoepoxyretinoate intraperitoneally and subcutaneously had good growth response in vitamin A-deficient rats. 5. 5,6-Monoepoxyretinoic acid, when given intraperitoneally as the sodium salt, was 157% as active as all-trans-retinyl acetate. 6. Methyl 5,6-monoepoxyretinoate was hydrolysed to the epoxy acid by rat-liver homogenate. It had 35% of the biological activity of all-trans-retinyl acetate in the rat when given orally.
| S-EPMC1270439 | biostudies-other
Project description:1. Oxidation of vitamin A acetate with monoperphthalic acid gave 5,6-monoepoxyvitamin A acetate, C(22)H(32)O(3), obtained as pale-yellow crystals, m.p. 65-66 degrees . 2. Saponification of 5,6-monoepoxyvitamin A acetate yielded 5,6-monoepoxyvitamin A alcohol, which was readily oxidized with manganese dioxide to 5,6-monoepoxyvitamin A aldehyde, obtained as yellow crystals, m.p. 101-102 degrees . It was the most stable of all the epoxy compounds studied. 3. Treatment of the 5,6-epoxy compounds with ethanolic hydrochloric acid gave the corresponding 5,8-epoxy (furanoid) compounds. 5,8-Monoepoxyvitamin A aldehyde was obtained as crystals, m.p. 104-105 degrees , but was very unstable. 4. Crystalline semicarbazones and phenylhydrazones with constant melting points and characteristic spectra were prepared from 5,6- and 5,8-monoepoxyvitamin A aldehyde. 5. Reduction of 5,6- and 5,8-monoepoxyvitamin A aldehyde with lithium aluminium hydride gave the corresponding 5,6- and 5,8-monoepoxyvitamin A alcohol. 6. 5,6- and 5,8-Monoepoxyvitamin A aldehyde were fed to vitamin A-deficient rats, and the compounds obtained from the livers of rats were indistinguishable from the reduction products obtained with lithium aluminium hydride. 7. The structures of the epoxy compounds were confirmed by their chromatographic behaviour, elemental analyses, ultraviolet-, visible- and infrared-absorption spectra and nuclear-magnetic-resonance spectra.
| S-EPMC1215172 | biostudies-other
Project description:1. Treatment of 3-dehydroretinyl acetate with aqueous hydrobromic acid resulted in the formation of retro-3-dehydroretinyl acetate, which, on alkaline hydrolysis, gave the corresponding alcohol. 2. retro-3-Dehydroretinyl acetate was isomerized to 3-dehydrovitamin A when fed to vitamin A-deficient rats. 3. When retro-3-dehydroretinyl acetate was administered orally, it was hydrolysed to retro-3-dehydroretinol in the rat intestine, isomerized to 3-dehydroretinol and esterified before being transported to the liver for storage. 4. When administered intraperitoneally, both 3-dehydrovitamin A and retro-3-dehydrovitamin A were accumulated in liver and other tissues, whereas after enterectomy 3-dehydrovitamin A was not detected anywhere in the body. 5. The small intestine was shown to be the major site of conversion of retro-3-dehydrovitamin A into 3-dehydrovitamin A. 6. The extent of conversion of retro-3-dehydroretinyl acetate into 3-dehydrovitamin A was much smaller than that of the conversion of retro-retinyl acetate into vitamin A. 7. The biological potency of retro-3-dehydroretinyl acetate, determined by the rat-growth assay, was 2.6% of that all-trans-retinyl acetate, when given orally.
| S-EPMC1186787 | biostudies-other
Project description:The incorporation of the trifluoromethoxy group into organic molecules has become very popular due to the unique properties of the named substituent that has a "pseudohalogen" character, while the chemical properties of the synthesized compound, especially heterocycles with such a group, are less studied. As trifluoromethoxy-substituted pyrazines are still unknown, we have developed efficient and scalable methods for 2-chloro-5-trifluoromethoxypyrazine synthesis, showing the synthetic utility of this molecule for Buchwald-Hartwig amination and the Kumada-Corriu and Suzuki and Sonogashira coupling reactions. Some comparisons of chlorine atom and trifluoromethoxy group stability in these transformations have been carried out.
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Project description:1. Oxidation of methyl retinoate with monoperphthalic acid gave methyl 5,6-epoxyretinoate, obtained as pale-yellow crystals, m.p. 89 degrees . 2. The structure of the epoxide was confirmed by its ultraviolet, infrared, nuclear-magnetic-resonance and mass spectra. 3. The biological properties of the epoxide were investigated in male and female rats, and were found to be qualitatively similar to those of retinoic acid and methyl retinoate. 4. When administered to male rats reared on a vitamin A-free diet, the epoxide permitted growth although it did not maintain good general health. 5. Rats given a vitamin A-free diet and supplements of the epoxide had degenerate testes. 6. Female rats, maintained on a vitamin A-free diet containing retinoic acid and given supplements of the epoxide during pregnancy, resorbed their foetuses and failed to deliver litters. 7. The threshold of the electroretinogram response in male rats reared on a vitamin A-free diet with supplements of the epoxide was elevated above normal and was similar to that of rats maintained with methyl retinoate. 8. The oral administration of the epoxy acid to rats did not result in the accumulation of the corresponding epoxy alcohol in their livers.
| S-EPMC1270192 | biostudies-other
Project description:Amorphous isomerically pure biliverdin IX alpha is readily prepared in more than 70% yield by dehydrogenation of bilirubin with 2,3-dichloro-5,6-dicyanobenzoquinone in dimethyl sulphoxide under carefully controlled conditions. Crystalline biliverdin IX alpha and amorphous [14C]biliverdin can be obtained similarly in more than 40+ yield. The pure crystalline pigment was characterized by elemental analysis, methylation, chemical and enzymic reduction to bilirubin, i.r.- and u.v.-visible-absorption spectroscopy, n.m.r. spectroscopy and field-desorption mass spectrometry, and its solubility was determined. Under certain conditions, dehydrogenation, gave biliverdin contaminated with III alpha and XIII alpha isomers as a result of disproporationation of bilirubin. Formation of non-IX alpha isomers depends on the concentrations of the reagents and the order in which they are mixed, and occurs under neutral anaerobic conditions. Free-radical reactions probably are responsible, suggesting that the first step in the deydrogenation of bilirubin with 2,3-dichloro-5,6-dicyanobenzoquinone in dimethyl sulphoxide is formation of a bilirubin cation radical, rather than hydride ion abstraction.
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Project description:Vascular disrupting agents (VDA) represent a novel approach to the treatment of cancer, resulting in collapse of tumor vasculature and tumor death. 5,6-Dimethylxanthenone-4-acetic acid (DMXAA) is a VDA currently in advanced Phase II clinical trials, yet its precise mechanism of action is unknown despite extensive preclinical and clinical investigations. The data presented herein demonstrate that DMXAA is a novel and specific activator of the TBK1-IRF-3 signaling pathway. DMXAA treatment of primary murine macrophages resulted in robust IRF-3 activation, a ~750-fold increase in IFN-beta mRNA and, in contrast to the potent Toll-like receptor 4 (TLR4) agonist, lipopolysaccharide (LPS), signaling was independent of mitogen-activated protein kinase (MAPK) activation and elicited minimal NF-kappaB-dependent gene expression. DMXAA-induced signaling was critically dependent on the IRF-3 kinase, TBK1, and IRF-3, but MyD88-, TRIF-, IPS-1/MAVS-, and IKKbeta-independent, thus excluding all known TLRs and cytosolic helicase receptors. DMXAA pretreatment of murine macrophages induced a state of tolerance to LPS and vice versa. In contrast to LPS stimulation, DMXAA-induced IRF-3 dimerization and IFN-beta expression were inhibited by salicylic acid (SA). These findings detail a novel pathway for TBK-1-mediated IRF-3 activation and provide new insights into the mechanism of this new class of chemotherapeutic drugs. Keywords: DMXAA, IRF-3, TBK1, IFN-beta, Salicylic acid, TLR
2007-03-08 | GSE7194 | GEO
Project description:Tantalum disulfide (TaS2) two-dimensional film material has attracted wide attention due to its unique optical and electrical properties. In this work, we report the preparation of 1?T-TaS2 quantum dots (1?T-TaS2 QDs) by top-down method. Herein, we prepared the TaS2 QDs having a monodisperse grain size of around 3?nm by an effective ultrasonic liquid phase exfoliation method. Optical studies using UV-Vis, PL, and PLE techniques on the as-prepared TaS2 QDs exhibited ultraviolet absorption at 283?nm. Furthermore, we found that dimension reduction of TaS2 has led to a modification of the band gap, namely a transition from indirect to direct band gap, which is explained using first-principle calculations. By using quinine as reference, the fluorescence quantum yield is 45.6%. Therefore, our results suggest TaS2 QDs have unique and extraordinary optical properties. Moreover, the low-cost, facile method of producing high quality TaS2 QDs in this work is ideal for mass production to ensure commercial viability of devices based on this material. TaS2 quantum dots having a monodisperse grain size of around 3?nm have been prepared by an ultrasonic liquid phase exfoliation method, it has been found that the dimension reduction of TaS2 has led to a transition from indirect to direct band gap that results in the unique and extraordinary optical properties (PL QY: 45.6%).
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Project description:Three solution-processable D-A-type conjugated polymers P1, P2 and P3 were successfully synthesized via the Pd-catalyzed Stille cross-coupling copolymerization approach, with 6,8-Dibromo-3,3-bis-decyl-3,4-dihydro-2H-thieno[3,4-b][1,4] dioxepine (M1) and 2,5-Bis(trimethylstannanyl)thiophene (M3) as the donor units and 4,7-Dibromo-5,6-difluoro-2-(2-hexyl-decyl)-2H-benzotriazole (M2) as the acceptor unit, wherein the feed ratio of the three units was 1:3:4 (M1:M2:M3, the same below), 1:1:2 and 3:1:4 for P1, P2, and P3, respectively. The results obtained by our test showed that the feed ratio between the D and A units had a significant effect on both the electrochemical and the spectroelectrochemical properties of the three polymers. The copolymers exhibited a gradually deepening red color in neutral state with the increase of M1 content and then turned to a transmissive grey color in the oxidation state. Also, three copolymers showed good performance in electrochromic parameters, which mainly consists of optical contrast, response time, and coloration efficiency. In general, the excellent electrochromic performances of the copolymers make them outstanding candidates for electrochromic material applications.
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Project description:In order to explore the applicability of the rejuvenated asphalt with wood tar as the main raw material, the orthogonal test was used to determine the optimal ratio of wood tar-based rejuvenator. The physical properties, rheological properties and components of matrix asphalt, aged asphalt, wood tar-based rejuvenated asphalt and commercial RA-102# rejuvenated asphalt were tested and compared. The results show that the optimal ratio of wood tar-based rejuvenator is 15wt% wood tar, 0.3wt% biomass fiber, 5wt% plasticizer, 0.3wt% compatibilizer, and 1wt% stabilizer of the mass of aged asphalt. Wood tar-based rejuvenator can restore the physical properties of the aged asphalt to meet the specification requirements. The synergistic effect of biomass fiber and plasticizer make the wood tar-based rejuvenated asphalt has good resistance to accumulated permanent deformation, but its low-temperature cracking resistance needs to be further improved. During the rejuvenation process of aged asphalt, the colloidal state changes from gel-state to sol-state, characterizing that the viscosity of asphalt decreased and the fluidity increased. Wood tar-based rejuvenator can react with aged asphalt to weaken the vibration strength of carbonyl and sulfoxide groups, so as to realize the recovery of service performance. Wood tar-based rejuvenator has better environmental protection and applicability, which is worthy of further study and promotion.
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